relnote: Protected by --quic_fix_beta_last_max. Fix conservative decrease for n-connection emulatio…

net/quic/core/congestion_control/cubic.h

Index: net/quic/core/congestion_control/cubic.h
diff --git a/net/quic/core/congestion_control/cubic.h b/net/quic/core/congestion_control/cubic.h
index 39c008c2c1403106afac7593b17dd0e166366af4..8c1afb3d5a3b90382e276779e2a3c7a00134863a 100644
--- a/net/quic/core/congestion_control/cubic.h
+++ b/net/quic/core/congestion_control/cubic.h
@@ -19,6 +19,10 @@
 
 namespace net {
 
+namespace test {
+class CubicTest;
+}  // namespace test
+
 class QUIC_EXPORT_PRIVATE Cubic {
  public:
   explicit Cubic(const QuicClock* clock);
@@ -50,15 +54,27 @@ class QUIC_EXPORT_PRIVATE Cubic {
   // TODO(jokulik):  Remove once the fix is enabled by default.
   void SetFixConvexMode(bool fix_convex_mode);
 
+  // If true, enable the fix for scaling BetaLastMax for n-nonnection
+  // emulation.  See b/33272010 for more information about the bug.
+  // TODO(jokulik):  Remove once the fix is enabled by default.
+  void SetFixBetaLastMax(bool fix_bet_last_max);
+
  private:
+  friend class test::CubicTest;
+
   static const QuicTime::Delta MaxCubicTimeInterval() {
     return QuicTime::Delta::FromMilliseconds(30);
   }
 
-  // Compute the TCP Cubic alpha and beta based on the current number of
-  // connections.
+  // Compute the TCP Cubic alpha, beta, and beta-last-max based on the
+  // current number of connections.
   float Alpha() const;
   float Beta() const;
+  float BetaLastMax() const;
+
+  QuicByteCount last_max_congestion_window() const {
+    return last_max_congestion_window_;
+  }
 
   const QuicClock* clock_;
 
@@ -107,6 +123,10 @@ class QUIC_EXPORT_PRIVATE Cubic {
   // TODO(jokulik):  Remove once the cubic convex experiment is done.
   bool fix_convex_mode_;
 
+  // Fix beta last max for n-connection-emulation.
+  // TODO(jokulik):  Remove once the corresponding experiment is done.
+  bool fix_beta_last_max_;
+
   DISALLOW_COPY_AND_ASSIGN(Cubic);
 };